1. Field of the Invention
The field of the invention is that of installations for the mixing of fluids by means of a system for the stirring of the mixture. More particularly, the installation of the invention is designed for the mixing of a liquid phase with a gas phase, enabling the contact between the two phases to be optimized.
The invention is applicable preferably to the treatment of stored, waste or filtered water by the transfer of an oxidizing gas into this water. In this case, it displays the functions of a turbojet with mass transfer.
However, those skilled in the art could envisage its use for the treatment of other liquids or, again, for other mixtures of liquids.
2. Description of the Prior Art
The following are the main aims, in the light of prevailing standards, in the treatment of water with a view to the distribution of water for consumption:
the elimination of suspended matter; PA1 the elimination of organic matter; PA1 the elimination of troublesome ions; PA1 sterilization. PA1 firstly, at least with two turbines arranged in stages, the rotational axis of which is the same as the axis of symmetry of the installation; and PA1 secondly, with structures forming counter-blades placed in an alternating position with the turbines. PA1 said fluid mixture is placed under pressure in the vessel, the treatment fluid being introduced by means of a pressure-reducing device such as a hydro-injector or a liquid jet vacuum pump and/or a compression device such as a pump, compressor or water ring pump; PA1 said vessel is at least partially immersed in a reservoir of liquid to be treated, so as to subject it, continuously or cyclically, to a partial treatment; PA1 at least two vessels according to the invention are associated so as to work in parallel or in series.
The standard treatment system most frequently comprises a succession of physical/chemical steps of the coagulation-flocculation-decantation-filtration type.
After the filtration operation, it is known that water should then be rid of pathogenic micro-organisms by means of oxidizing agents (ozone, chlorine etc.) or radiation (UV radiation) or again by a refining treatment using active coal in granular or powder form (the elimination of micropollutants, heavy trace metals, and unwholesome flavors or odors).
The use of ozone is recognized as being efficient not only in bactericidal and virulicidal conditions, but also in combined steps of treatment by ozonation-coagulation, ozonation-flottation, ozonation-adsorption on filtering media (with the possibility of biological activity on the filter), without overlooking the more standard applications such as iron extraction and demanganizing or the elimination of flavors and odors. Finally, it is known that ozone has an oxidizing effect on a number of micropollutants (phenols, certain detergents etc.): see B. Langlais, Nouveau developpement de l'ozonation en eau potable et technologie appropriee (New Development of Ozonation in Potable Water and Appropriate Technology) in L'eau, l'industrie, les nuisances (Water, Industry, Nuisance), No. 109, April 1987, pp. 28 to 30.
There are several known types of mixers used in water treatment systems. These mixers may be constituted by injection systems (porous membranes, depression-creating diffusers, emulsifying machines also known as liquid jet vacuum pumps or hydro-injectors), static mixers or dynamic mixers (for example with driven turbine or stirrers).
These known mixers are generally located upstream from the contact vessels (also known as contactors) designed as to keep the oxidizing gas in contact, for a predetermined time, with the flow of liquid to be treated.
Thus, for example, the French patent application No. 90 06969 dated May 31, 1990, filed on behalf of the present applicant, describes an installation comprising, for example, successively a transfer machine for the addition of the treatment gas to the liquid to be treated, a module for the enforced dissolving of the treatment gas in the liquid and a contactor module. The enforced dissolving module described in this document is constituted by a recirculator device constituted by a vessel comprising a first central chamber forming a gas exhaust conduit and a second annular recirculation chamber coaxial to the exhaust conduit. The two chambers are separated by a wall and communicate with each other at their lower and upper parts so as to enable the recirculation of the treatment medium by cyclical passage from one to the other.